Over the first five years of funding of this program project grant (PPG), our laboratory has been applying an interdisciplinary approach for defining metabolic abnormalities of liver, pancreatic islet B-cells, and skeletal muscle in diabetes and obesity. Over the same time period, other members of this PPG team have developed technologies for functional imaging, targeted delivery of genes and other molecular cargo, and customized gene activation switches. The most compelling advances made by the PPG team have occurred in the area of pancreatic islet biology and related technologies. We have therefore chosen to focus the competitive renewal of this application on development of new strategies for understanding and reversing B-cell dysfunction of type 2 diabetes. The goal of this project (Project 1) is to investigate and validate novel pathways for control of B-cell function and growth that have emerged from our work in the prior funding period. The project will make extensive use of extraordinary technologies resident in Core B for B-cell specific gene delivery in adult animals, and in Core C for comprehensive MS- and NMR-based metabolic analysis of islets and B-cell lines. The specific aims of the project are: 1) To investigate mechanisms by which manipulation of the homeodomain transcription factor Nkx6.1 and its target genes affect glucose-stimulated insulin secretion (GSIS) in pancreatic islets;2) To investigate mechanisms by which manipulation of the homeodomain transcription factor Nkx6.1 and its target genes affect pancreatic islet growth;3) To test the potential protective or restorative effect of Nkx6.1 and its target genes in preservation of B-cell mass and function in cellular and animal models of type 2 diabetes .